@voitanos/jest-preset-spfx v1.4.1

jest-preset-spfx

A Jest preset configuration for SharePoint Framework (SPFx) projects.

NOTE: This preset does not contain any support for SPFx projects that utilize React.

See the related packages jest-preset-spfx-react15 & jest-preset-spfx-react16 if you are leveraging React in your SPFx projects.

Installation

1. Install Jest & this preset using your package manager of choice:

   npm install jest @voitanos/jest-preset-spfx --save-dev

   This will install @types/jest, ts-jest & identity-obj-proxy as dependencies in your project.

   The postinstall script will verify you have a ./config/jest.config.json file and update your package.json scripts with two scripts for running Jest tests with this configuration: test & test:watch.

   If the configuration file is not present, it will create it. If it is present, it will verify the minimal properties.

   NOTE: A specific version of ts-jest is used to support the SPFx supported version of TypeScript as more current versions of ts-jest require newer versions of TypeScript that is not yet supported by SPFx.

Validating Installation

To validate a successful install, do one of the following two things:

Option 1: Add example tests

1. Copy the folder examples from the installed package (also found here in the source repo) into the project's src folder.

2. Execute Jest to run the tests:

   npm test

3. Observe four (4) passing tests.

Option 2: Create your own test

1. Add a new file SampleTests.spec.ts to the ./src/webparts folder with the following code:

   import 'jest';
   
   test('1+1 should equal 2', () => {
     const result = 1+1;
     expect(result).toBe(2);
   });

2. Execute Jest to run the tests:

   npm test

3. Observe a single (1) passing test.

How it works

This package contains a base Jest configuration that your project will inherit. It does this by using the preset property to @voitanos/jest-preset-spfx in the jest.config.json file.

References

Package.json NPM scripts

Two scripts are added to the package.json scripts section:

• test: Run Jest and specify the configuration file to use: npm test.
• test:watch: Run Jest and specify the configuration file to use, but run in watch mode so when files change, it will automatically re-run the tests: npm run test:watch.

Jest preset configuration for SPFx

The following preset is used for SPFx projects:

Explanation of select configuration properties above: jest-preset.json

• collectCoverage, coverageDirectory, collectCoverageFrom & coverageReporters: collects code coverage statistics and generates associated reports in the ./temp/test folder
• moduleNameMapper:
  • when Jest sees a request for a CSS/SCSS file in the source files, it effectively ignores it using the identity-obj-proxy package
  • when jest sees a request for en-us.json, it is provided a helper path to find the file
• testMatch: all tests found either in a special __tests__ folder or within the src folder with the following names will be found:
  • *.spec.ts
  • *.spec.tsx
  • *.spec.js
  • *.spec.jsx
  • *.test.ts
  • *.test.tsx
  • *.test.js
  • *.test.jsx
• transform: the Jest preprocessor will transpile all TypeScript files to JavaScript before running the tests.